Latitude and Climate

One of the most important factors
determining your climate is your latitude.
Between 23.5S and 23.5N latitude we have the tropics
- where high temperatures are the norm, and the sun can beat down from
directly overhead once or twice each year. From 23.5N to 66.5N
and between 23.5S and 66.5S are the temperate zones, where there are clear spring/summer/fall/winter
seasons. From 66.5N to the North Pole we have the Arctic,
and from 66.5S to the South Pole, the Antarctic.
In these arctic zones the sun is above the horizon at midnight for part
or all of the summer and never rises at all during some day(s) in the
winter. At the pole, daily motion is parallel to the horizon.

With the meridian
diagram, we can find out the altitude of the sun at
noon at any season as observed from any place on Earth. This
information can be very helpful in planning a garden or a house
so that the sun
will shine on the areas we want it to. Knowing the sun's altitude
at noon in the summer is also useful in figuring out how to shade your
windows against the noon summer sun, while allowing the winter sun
to shine in and keep you warm in the interior. The following meridian
diagram is sketched for Ames, Iowa latitude of
42 degrees
N.

Interactive
Graphic 5-1-1 Click
the Play button at the bottom right.

1) In
the interactive graphic above, the angle
between the arrow pointing to the celestial equator and the arrow pointing to the
Sun is what at the summer solstice?

Equal
to 90 deg minus the
latitude of the observer
Minus the tilt of Earth's axis,
or -23.5 degrees
Equal to the tilt of Earth's axis,
or 23.5 deg

Just
as in Question 5-1-1 above, at the winter
solstice, the angle between the arrow pointing to the sun and the
arrow pointing to the celestial equator in the interactive graphic above
is equal to the tilt of Earth's axis, 23.5 degrees. The tilt of
the Earth's axis results in an apparent annual
motion of the sun from -23.5 deg in December to +23.5 deg in June, on
the date of the summer
solstice.

Thus,
the altitude of the sun at noon in Ames at the winter solstice
is 48 degrees minus 23.5
degrees = 24.5 degrees. This is true because the celestial
equator is at 90 minus the local latitude = 90 - 42 = 48 deg altitude,
as seen from Ames. At the winter solstice, the sun is 23.5
degrees S. of the CE, so the sun is lower in the sky by 23.5 degrees,
which means it reaches an altitude of 24.5 degrees.

2) At
the summer solstice the
sun transits the meridian
in Ames, Iowa
at what altitude?

90 + 23.5 = 113.5 deg
90 - 23.5 = 66.5 deg
48+23.5 = 71.5 deg

Climate
Zones

Latitudes
between 23.55 and 23.5 N are called the Tropics. Latitudes between
23.5 and 66.5 N or S are the Temperate
Zones and between 66.5 and 90 N or S are the Arctic (and Antarctic)
zones.

3) North
of 66.5 N latitude, in
the Arctic, there is sunshine
for how
many hours per day at midsummer?

12 Hours
24 Hours
No Hours

4) North of 66.5 N latitude, in the Arctic, how many hours of sunshine
are there in mid-winter?

12 Hours
24 Hours
No Hours

5) Between
23.5 N and 23.5 S latitude it is possible for the sun
to pass through what
special point?